The plastic laminated card industry has relied on the process of hot lamination to produce credit cards, identification cards, loyalty cards and other flat tokens containing information. This process consists of layering a variety of plastic sheets which have a variety of functions such as opacity, graphics and protective layers into the finished stack. The layers can be opaque or clear and may contain functional elements such as magnetic stripes. Once the desired layers have been assembled, the assembly is subjected to heat and pressure to fuse the various layers together to form a continuous structure. As most wallets and purses show, hundreds of millions of cards have been produced to meet a variety of needs. For many situations the card is provided without separate charge, so providers are conscious of cost.
A typical assembly consists of a center layer, a front and a back graphic layer that are typically pre-printed, a magnetic strip and clear protective layers which provide gloss and protect the printed graphics. Often, security features, such as holograms, are included in the structure. Smart cards are produced by adding a microprocessor and chip plate to the card after lamination by milling a recess and mounting the integrated chip plate and integrated circuit. The IC may be attached to an antenna, if desired to allow the IC to communicate through RF in a contactless mode. The preferred materials for existing hot laminated cards include layers made from polyvinylchloride (PVC), polypropylene, polycarbonate, polyester, and other suitable plastics with a melt temperature in the range of approximately 110° C. to 190° C.
The hot lamination process used to produce cards and the like represents the vast majority of installed card production capacity on a global basis. Other processes such as cold lamination, which relies on adhesive bonding, have been developed but have been implemented on a limited basis. Any new card structures are more useful if compatible with existing hot lamination processes.
The desired attributes of a finished laminated card include high gloss, undistorted graphics and uniform, smooth surfaces. In addition, for financial transaction and identification cards, the structure must meet ISO standards. ISO standards for cards define performance requirements such as temperature and humidity resistance, flexibility, lamination integrity, flatness and physical dimensions. The scope of application for an identification card will determine the physical characteristics of the card. Physical characteristics of the cards (ID-1, ID-2 and ID-3) are described in ISO/IEC 7810:2003 Identification cards—Physical characteristics. The tests for cards with magnetic stripes, integrated circuits, or optical memory are described in ISO/IEC 10373-1 Identification cards—Test methods. The requirements for the contacts in integrated circuit cards are covered by ISO/IEC 7816-1 Identification cards—Integrated circuit cards with contacts. The specification for embossed characters is given within ISO/IEC 7811-1:2002 Identification cards—Recording technique—Part 1: Embossing. ISO 7813 sets out requirements to be met by financial transaction cards. Whereas, ISO/IEC 7501 covers machine readable travel documents, such as passports and visas. Another type of identification card is the thin flexible card (TFC), which is covered by ISO/IEC 15457. Additional relevant standards are identified in Appendix A. All these standards are incorporated herein by reference.
Incorporating electronic components prior to hot lamination, such as integrated circuits (ICs), antennas, batteries, displays, switches and other circuitry, presents significant difficulty when the hot lamination process is done. The primary difficulty results from the various heights of the different components and the various heat transfer characteristics of the materials employed. Unless these are adequately addressed, performing the hot lamination process with electronic components in place in the layers to be laminated will result in surface defects, unacceptable warping or damage to the internal components.
RFID antennas and their chips have been incorporated into hot laminated cards previously. The antennas, either copper wire, etched metal, or printed silver, are typically connected to a small IC, which is provided as an inlay and is sandwiched into the structure as a discrete layer. The hot lamination process yields acceptable results for RFID primarily because the IC can be limited to a small size and the antenna can be kept thin. However, more complex structures make it more difficult to yield acceptable results, due to the number and size of the components and the need to meet visual and ISO quality standards.
Other approaches to incorporate electronic components in cards involve the formation of cavities through mechanical means such as milling. In one such approach, the card core is milled to produce a cavity that receives the electronic components. After placement of the components, a potting liquid may be added to the milled-out area to level the structure. This approach is relatively slow and does not yield a cost-effective, high volume manufacturing process relative to a simple lamination process.
A variety of approaches have been proposed to address the desire to incorporate more elaborate electronics into card structures. German references, Patentschrift DE 19923138 C1 and Offenlegungsschrift DE 10219306 A1, teach an approach whereby a separate structure is built to contain the electronic components by utilizing loose films which are then hot laminated to fuse the layers. This approach is difficult to implement in high volume due to the inherent variability in raw materials and requires additional steps in the manufacturing process, going beyond lamination, to achieve the desired results. The use of a separate structure to mount the electronic components and subsequently adding discrete layers does not adequately provide a reproducible means to incorporate electronic components cost effectively.
The prior art requires use of films with specific thicknesses that may not match the thickness of the components exactly. To avoid this problem, the manufacturer requires very specific component thicknesses to match the available films. Manufacturing variability of both the components and films will often result in inferior results, due to mismatched heights. Finally, this approach attempts to compensate for the variability of both an individual component and film, but it does not address the increased variability introduced when multiple components are used in a layered structure. The manufacturing process itself introduces the need for tolerances in die cuts and placement that must be accounted for.
One key aspect of certain ISO standards requires a specific thickness for the overall card. ISO standards specify an overall thickness of 0.030±0.002 inches for the card. Because the cards require two graphics layers, which are typically 0.005 inches each, and a clear protective layer, which is typically 0.002 inches, this leaves a total of 0.016 to 0.020 inches available to incorporate the electronic core layers with the functional electronic components.
This requirement presents special challenges if a battery is to be incorporated in the card. Current pre-packaged battery constructions are typically 0.012 to 0.016 inches thick, which does not leave sufficient thickness remaining to easily embed the battery and provide adequate opacity to hide the component. Additionally, current battery packaging techniques result in highly variable package dimensions that must be accounted for during the lamination process.
The ISO standards specifying flexibility also present specific challenges related to incorporation of electronic components into the card. Circuit integrity is an important consideration when producing a flexible product. The lamination process must produce a structure that minimizes stresses on the various components. A variety of electronic components may be included in the card, such as IC's, antennas, switches, batteries, magnetic stripe emulators and displays. Each component may have a different thickness, size, and flexibility but must be packaged in the card and result in desired overall card flexibility while maintaining electrical integrity of the electronic circuits.
It is highly desirable to incorporate a display as part of the electronic package of certain cards. Traditional display technologies are not suitable for incorporation into an ISO compliant card. A variety of limitations are inherent in displays of the prior art. To successfully integrate a display, the preferred display is flexible, uses low power to minimize battery requirements, operates at less than 3V to minimize the number of electronic components required, and can be hot laminated using current processes.
There is a need for an electronic core structure with associated electronic components, which may include a display, that can be hot laminated and meets ISO standards for financial transaction and/or identification cards. In particular, parties producing cards for delivery to customers by applying customized final graphic layers need an electronic core structure that provides the functionality to satisfy customer needs.